BRIEF CONTENTS. in this web service Cambridge University Press. The constellation Taurus, the Bull, from the 1603 star atlas by Johann Bayer.

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BRIEF CONTENTS Preface xix 1 A Grand Tour of the Heavens 1 2 Light, Matter, and Energy: Powering the Universe 21 3 Light and Telescopes: Extending Our Senses 37 4 Observing the Stars and Planets:

1 BRIEF CONTENTS Preface xix 1 A Grand Tour of the Heavens 1 2 Light, Matter, and Energy: Powering the Universe 21 3 Light and Telescopes: Extending Our Senses 37 4 Observing the Stars and Planets: Clockwork of the Universe 67 5 Gravitation and Motion: The Early History of Astronomy 95 6 The Terrestrial Planets: Earth, Moon, and Their Relatives The Jovian Planets: Windswept Giants Pluto, Comets, and Space Debris Our Solar System and Others Our Star: The Sun Stars: Distant Suns How the Stars Shine: Cosmic Furnaces The Death of Stars: Recycling Black Holes: The End of Space and Time The Milky Way: Our Home in the Universe A Universe of Galaxies Quasars and Active Galaxies Cosmology: The Birth and Life of the Cosmos In the Beginning Life in the Universe 541 Epilogue 559 Appendix 1. Measurement Systems 561 Appendix 2. Basic Constants 561 Appendix 3. Planets and Dwarf Planets 562 Appendix 4. The Brightest Stars 564 Appendix 5. The Nearest Stars 566 Appendix 6. The Messier Catalogue 568 Appendix 7. The Constellations 570 Selected Readings 571 Glossary 575 Index 585 Jay M. Pasachoff collection The constellation Taurus, the Bull, from the 1603 star atlas by Johann Bayer.

Preface xix A GRAND TOUR OF THE HEAVENS 1 1.1 Peering through the Universe: A Time Machine 2 Figure It Out 1.1: Keeping Track of Space and Time 3 1.2 How Do We Study Things We Can t Touch?

2 CONTENTS NASA, ESA, and E. Sabbi (ESA/STScI)/R. O'Connell (University of Virginia) and the Wide Field Camera 3 Science Oversight Committee 1 Merging star clusters in 30 Doradus, in the Large Magellanic Cloud, imaged with the Hubble Space Telescope. Preface xix A GRAND TOUR OF THE HEAVENS Peering through the Universe: A Time Machine 2 Figure It Out 1.1: Keeping Track of Space and Time How Do We Study Things We Can t Touch? 3 Figure It Out 1.2: Scientifi c Notation Finding Constellations in the Sky 4 The Autumn Sky 6 The Winter Sky 7 Star Party 1.1: Using the Sky Maps 8 The Spring Sky 10 The Summer Sky How Do You Take a Tape Measure to the Stars? The Value of Astronomy 11 The Grandest Laboratory of All 11 Origins 11 A Closer Look 1.1: A Sense of Scale: Measuring Distances What Is Science? Why Is Science Far Better Than Pseudoscience? 16 2 LIGHT, MATTER, AND ENERGY: POWERING THE UNIVERSE Studying a Star Is Like Looking at a Rainbow Blackbodies and Their Radiation 22 ATST/NSO/NSF, image by L. Phelps Figure It Out 2.1: The Nature of Light 23 Figure It Out 2.2: Blackbody Radiation and Wien s Law 24 Figure It Out 2.3: Blackbody Radiation and the Stefan-Boltzmann Law 25 An artist's rendering of the Advanced Technology Solar Telescope with its 4-m-diameter mirror, now being erected on Haleakala, Maui, Hawaii.

ix 2.3 What Are Those Missing Colors and Where Are They? 25 2.4 The Story Behind the Bohr Atom 27 2.5 The Doppler Effect and Motion 30 Figure It Out 2.

3 ix 2.3 What Are Those Missing Colors and Where Are They? The Story Behind the Bohr Atom The Doppler Effect and Motion 30 Figure It Out 2.4: Temperature Conversions 31 3 LIGHT AND TELESCOPES: EXTENDING OUR SENSES The First Telescopes for Astronomy How Do Telescopes Work? Modern Telescopes 41 Figure It Out 3.1: Light-Gathering Power of a Telescope 42 Current Large Telescopes Around the World 42 Figure It Out 3.2: Changing Units 45 The Next Generation of Optical and Infrared Ground-Based Telescopes The Big Picture: Mapping the Sky Amateurs Are Participating Glorious Hubble After Initial Trouble You Can t Look at the Sun at Night How Can You See the Invisible? 52 4 X-ray and Gamma-ray Telescopes 52 Telescopes for Ultraviolet Wavelengths 54 Infrared Telescopes 55 Radio Telescopes 55 The Major New Radio Projects 56 Figure It Out 3.3: Angular Resolution of a Telescope 57 A Closer Look 3.1: A Night at Mauna Kea 59 OBSERVING THE STARS AND PLANETS: CLOCKWORK OF THE UNIVERSE The Phases of the Moon and Planets Celestial Spectacles: Eclipses 70 Star Party 4.1: Observing Total Solar Eclipses 72 Jay M. Pasachoff collection The frontispiece of Galileo s Dialogo, published in Eerie Lunar Eclipses 73 A Closer Look 4.1: Colors in the Sky 74 Glorious Solar Eclipses Twinkle, Twinkle, Little Star The Concept of Apparent Magnitude 78 Figure It Out 4.1: Using the Magnitude Scale Rising and Setting Stars 80 A Closer Look 4.2: Photographing the Stars 80 Figure It Out 4.2: Sidereal Time Celestial Coordinates to Label the Sky The Reason for the Seasons 82 Star Party 4.2: The Paths of the Moon and Planets Time and the International Date Line Calendars Keeping Time 90 5 GRAVITATION AND MOTION: THE EARLY HISTORY OF ASTRONOMY A Brief Survey of the Solar System 95

x 6 NASA/JPL-Caltech/Malin Space Science Systems Star Party 5.1: Prograde and Retrograde Motions 96 5.2 The Earth-Centered Astronomy of Ancient Greece 97 5.

5 Johannes Kepler and His Laws of Orbits 101 Lives in Science 5.2: Tycho Brahe 102 Kepler s First Law 103 Kepler s Second Law 103 A Closer Look 5.2: Kepler s Laws 104 Lives in Science 5.

4 x 6 NASA/JPL-Caltech/Malin Space Science Systems Star Party 5.1: Prograde and Retrograde Motions The Earth-Centered Astronomy of Ancient Greece A Heretical Idea: The Sun-Centered Universe 98 A Closer Look 5.1: Ptolemaic Terms 98 Lives in Science 5.1: Copernicus The Keen Eyes of Tycho Brahe Johannes Kepler and His Laws of Orbits 101 Lives in Science 5.2: Tycho Brahe 102 Kepler s First Law 103 Kepler s Second Law 103 A Closer Look 5.2: Kepler s Laws 104 Lives in Science 5.3: Johannes Kepler 104 Kepler s Third Law The Demise of the Ptolemaic Model: Galileo Galilei 105 Figure It Out 5.1: Kepler s Third Law 106 Lives in Science 5.4: Galileo Galilei On the Shoulders of Giants: Isaac Newton 108 Star Party 5.2: Galileo s Observations 109 A Closer Look 5.3: Newton s Law of Universal Gravitation 110 Figure It Out 5.2: Newton s Version of Kepler s Third Law 110 A self-portrait mosaic image of Curiosity, the lander of NASA's Mars Science Laboratory, with Gale Crater's Mount Sharp at background right. 5.8 Clues to the Formation of Our Solar System 111 Lives in Science 5.5: Isaac Newton 111 Figure It Out 5.3: Orbital Speed of Planets 112 THE TERRESTRIAL PLANETS: EARTH, MOON, AND THEIR RELATIVES Earth: There s No Place Like Home 120 A Closer Look 6.1: Comparative Data for the Terrestrial Planets and Their Moons 120 The Earth s Interior 121 A Closer Look 6.2: Density 122 Continental Drift 122 Tides 124 The Earth s Atmosphere 124 The Van Allen Belts The Moon 127 The Moon s Appearance 127 The Lunar Surface 130 A Closer Look 6.3: The First People on the Moon 130 The Lunar Interior 135 The Origin of the Moon 135 Rocks from the Moon Mercury 137 Ronald Dantowitz (Clay Center Observatory) and Jay M. Pasachoff (Williams College)/National Geographic Society Committee for Research and Exploration The Rotation of Mercury 137 Venus's silhouette shows, as do sunspots, in the middle of the six-hour transit of Venus across the face of the Sun on June 5/6, 2012.

xi NASA/JPL/Space Science Institute Saturn's moon Titan in front of the planet and its rings, from NASA's Cassini spacecraft in 2012. Mercury s History 138 A Closer Look 6.

143 6.4 Venus 143 Transits of Venus 143 The Atmosphere of Venus 144 The Rotation of Venus 144 Why Is Venus So Incredibly Hot?

5 xi NASA/JPL/Space Science Institute Saturn's moon Titan in front of the planet and its rings, from NASA's Cassini spacecraft in Mercury s History 138 A Closer Look 6.4: Naming the Features of Mercury 139 Mercury Observed from the Earth 139 Spacecraft Views of Mercury 139 Mercury Research Rejuvenated 141 Mercury from MESSENGER 141 Continuing Exploration of Mercury Venus 143 Transits of Venus 143 The Atmosphere of Venus 144 The Rotation of Venus 144 Why Is Venus So Incredibly Hot? 145 Spacecraft Observations of Venus s Atmosphere 146 Radar Observations of Venus s Surface 147 Venus Exploration in the 21st Century Mars 149 Characteristics of Mars 150 Mars s Surface 151 Mars s Atmosphere 152 A Closer Look 6.5: Mars Exploration Rovers, Mars Phoenix, and Mars Science Lab s Rover Curiosity 155 Mars s Satellites 157 The Search for Life on Mars 157 Crewed Missions to Mars Jay M. Pasachoff, Glenn Schneider, and colleagues/stsci/nasa/esa Jupiter with the Hubble Space Telescope, a composite of an ultraviolet and an infrared image made as part of one of the authors' observations made in 2012 while a transit of Venus as seen from Jupiter was dimming that giant planet by 0.01%. THE JOVIAN PLANETS: WINDSWEPT GIANTS Jupiter 168 A Closer Look 7.1: Comparative Data for the Major Worlds 168 Star Party 7.1: Observing the Giant Planets 169 Spacecraft to Jupiter 169 Figure It Out 7.1: The Size of Jupiter 169 The Great Red Spot 170 Jupiter s Atmosphere 170 Jupiter s Interior 172 Jupiter s Magnetic Field 172 Jupiter s Ring 173 Jupiter s Amazing Satellites 173 A Closer Look 7.2: Jupiter and Its Satellites in Mythology Saturn 177 Saturn s Rings 177 Saturn s Atmosphere 179 Saturn s Interior and Magnetic Field 179 Saturn s Moon Titan 181 A Closer Look 7.3: Saturn s Satellites in Mythology 181 A Closer Look 7.4: Saturn s Rings and Moons from Cassini 183

see the solar corona surrounding the dark silhouette of the Moon. Saturn s Other Satellites 184 7.3 Uranus 184 Uranus s Atmosphere 185 Uranus s Rings 185 A Closer Look 7.

6 xii Jay M. Pasachoff/Williams College Eclipse Expedition/NSF The shadow of the Moon surrounds the eclipsed Sun in this view from a helicopter, above an Australian cloud-deck, of the 2012 total solar eclipse; we see the solar corona surrounding the dark silhouette of the Moon. Saturn s Other Satellites Uranus 184 Uranus s Atmosphere 185 Uranus s Rings 185 A Closer Look 7.5: Uranus and Neptune in Mythology 185 Uranus s Interior and Magnetic Field Neptune 187 Neptune s Atmosphere 188 Neptune s Interior and Magnetic Field 189 Neptune s Rings 190 Neptune s Moon Triton 190 A Closer Look 7.6: Naming the Rings of Neptune The Formation of the Giant Planets PLUTO, COMETS, AND SPACE DEBRIS Pluto 198 Pluto s Mass and Size 198 Pluto s Atmosphere 200 What Is Pluto? Kuiper-Belt Objects and Dwarf Planets 202 A Closer Look 8.1: Dwarf Planets Comets 204 The Composition of Comets 205 The Origin and Evolution of Comets 206 Halley s Comet 207 Comet Shoemaker-Levy Recently Observed Comets 210 Spacecraft to Comets 210 A Closer Look 8.2: Deep Impact Meteoroids 215 Types and Sizes of Meteorites 215 A Closer Look 8.3: February 15, 2013 An Exploding Meteor; A Nearby Asteroid 216 Meteor Showers 218 A Closer Look 8.4: Meteor Showers Asteroids 219 General Properties of Asteroids 219 Star Party 8.1: Observing a Meteor Shower 220 A Closer Look 8.5: The Extinction of the Dinosaurs 220 Asteroids Viewed Close Up 222 Near-Earth Objects 223 A Closer Look 8.6: Images from Curiosity on Mars 231 NASA/JPL-Caltech/UCAL/MPS/DLR/IDA The asteroid (4) Vesta, a mosaic of the highest-resolution images from NASA's Dawn spacecraft, which is now en route to (1) Ceres. 9 OUR SOLAR SYSTEM AND OTHERS The Formation of the Solar System 234 Collapse of a Cloud 234 Models of Planet Formation Extra-solar Planets (Exoplanets) 236

Exoplanets 244 Gravitational Microlensing 244 9.3 The Nature of Exoplanet Systems 244 9.4 Goldilocks Planets 246 9.5 Brown Dwarfs 246 9.6 Planetary Systems in Formation 246 10 Jay M.

7 xiii 10.3 The Sun and the Theory of Relativity 270 Lives in Science 10.1: Albert Einstein 271 A Closer Look 10.2: Solar Eclipses of Astrometric Method 237 Timing of Radio Pulsars 237 Periodic Doppler Shifts: The Doppler-Wobble Method 237 Transitioning Planets: The Blink Method 240 Direct Imaging of Exoplanets 244 Gravitational Microlensing The Nature of Exoplanet Systems Goldilocks Planets Brown Dwarfs Planetary Systems in Formation Jay M. Pasachoff/NSF The diamond ring effect along with reddish chromosphere and prominences mark the end of the 2012 total solar eclipse observed from Australia. OUR STAR: THE SUN What Is the Sun s Basic Structure? 256 The Photosphere 257 A Closer Look 10.1: The Most Common Elements in the Sun s Photosphere 258 The Chromosphere 259 The Corona 260 The Scientifi c Value of Eclipses Sunspots and Other Solar Activity 265 What Are Those Blemishes on the Sun? 265 Star Party 10.1: Observing Sunspots 266 The Solar-Activity Cycle 267 Fireworks on the Sun, and Space Weather 269 Filaments and Prominences STARS: DISTANT SUNS Colors, Temperatures, and Spectra of Stars 280 Taking a Star s Temperature 280 How Do We Classify Stars? 281 The Coolest Stars How Distant Are the Stars? 282 Figure It Out 11.1: Stellar Triangulation How Powerful Are the Stars? 285 A Closer Look 11.1: Using Absolute Magnitudes 286 Figure It Out 11.2: The Inverse-Square Law Temperature-Luminosity Diagrams 287 Figure It Out 11.3: A Star s Luminosity 289 A Closer Look 11.2: Proxima Centauri: The Nearest Star Beyond the Sun How Do Stars Move? 290 Proper Motions of Stars 290 Radial Velocities of Stars Social Stars : Binaries 292 Solar Dynamics Observatory's Atmospheric Imaging Assembly/LMSAL/NASA Pairs of Stars and Their Uses 292 A view of the Sun in the extreme ultraviolet part of the spectrum, showing million-degree gas held in place by the solar magnetic field.

xiv Figure It Out 11.4: Doppler Shifts 293 Figure It Out 11.5: Binary Stars 294 A Closer Look 11.3: A Sense of Mass: Weighing Stars 297 How Do We Weigh Stars?

8 xiv Figure It Out 11.4: Doppler Shifts 293 Figure It Out 11.5: Binary Stars 294 A Closer Look 11.3: A Sense of Mass: Weighing Stars 297 How Do We Weigh Stars? 297 The Mass-Luminosity Relation 297 Figure It Out 11.6: The Mass-Luminosity Relation Stars That Don t Shine Steadily Clusters of Stars Open and Globular Star Clusters 300 A Closer Look 11.4: Star Clusters in Our Galaxy 302 How Old Are Star Clusters? 303 A Closer Look 11.5: How We Measure Basic Stellar Parameters 305 HOW THE STARS SHINE: COSMIC FURNACES Starbirth 312 Collapse of a Cloud 312 The Birth Cries of Stars Where Stars Get Their Energy Atoms and Nuclei 317 Figure It Out 12.1: Energy Generation in the Sun 318 Subatomic Particles 318 NASA, ESA, CXC, SAO, the Hubble Heritage Team (STScI/AURA), and J. Hughes (Rutgers University) An optical and x-ray composite image of a supernova remnant, incorporating Hubble Space Telescope images showing the pink optical shell surrounding the x-ray images, shown in blue and green, from the Chandra X-ray Observatory. The supernova came from a supergiant star that exploded (Type Ia) 400 years ago in the Large Magellanic Cloud. The bubble is 23 light-years across. Isotopes 318 Radioactivity and Neutrinos Stars Shining Brightly Why Stars Shine Brown Dwarfs The Solar-Neutrino Experiment 322 Initial Measurements 322 Further Solar-Neutrino Experiments 323 Beyond Solar Neutrinos The End States of Stars THE DEATH OF STARS: RECYCLING The Death of the Sun 332 Red Giants 332 Planetary Nebulae 333 White Dwarfs 334 Summary of the Sun s Evolution 336 Binary Stars and Novae Supernovae: Stellar Fireworks! 337 Core-Collapse Supernovae 338 White-Dwarf Supernovae (Type Ia) 339 Observing Supernovae 341 Supernova Remnants 343 Supernovae and Us 343 Supernova 1987A! 343 A Closer Look 13.1: Searching for Supernovae 344 Cosmic Rays Pulsars: Stellar Beacons 349 Neutron Stars 349 The Discovery of Pulsars 349 What Are Pulsars? 350 The Crab, Pulsars, and Supernovae 351 Slowing Pulsars and Fast Pulsars 352 Binary Pulsars and Gravitational Waves 352 A Pulsar with a Planet 355 X-ray Binaries 355

xv 14 BLACK HOLES: THE END OF SPACE AND TIME 361 14.1 The Formation of a Stellar-Mass Black Hole 362 14.2 The Photon Sphere 362 14.

9 xv 14 BLACK HOLES: THE END OF SPACE AND TIME The Formation of a Stellar-Mass Black Hole The Photon Sphere The Event Horizon 363 A Newtonian Argument 363 Black Holes in General Relativity Time Dilation Properties of Black Holes 365 Rotating Black Holes 365 Measuring Black-Hole Spin Passageways to Distant Lands? Detecting a Black Hole 367 Hot Accretion Disks 367 Cygnus X-1: The First Plausible Stellar-Mass Black Hole 368 Other Black-Hole Candidates 369 Figure It Out 14.1: Binary Stars and Kepler s Third Law 369 The Strange Case of SS Supermassive Black Holes Moderation in All Things Gamma-ray Bursts: Birth Cries of Black Holes? 374 How Far Away Are Gamma-ray Bursts? 374 Models of Gamma-ray Bursts Mini Black Holes THE MILKY WAY: OUR HOME IN THE UNIVERSE Our Galaxy: The Milky Way The Illusion That We Are at the Center 384 Star Party 15.1: Observing the Milky Way Nebulae: Interstellar Clouds The Parts of Our Galaxy The Center of Our Galaxy All-Sky Maps of Our Galaxy Our Pinwheel Galaxy Why Does Our Galaxy Have Spiral Arms? Matter Between the Stars Radio Observations of Our Galaxy Mapping Our Galaxy Radio Spectral Lines from Molecules The Formation of Stars At a Radio Observatory A UNIVERSE OF GALAXIES The Discovery of Galaxies 414 The Shapley-Curtis Debate 414 Galaxies: Island Universes Types of Galaxies 417 Spiral Galaxies 417 Elliptical Galaxies 420 Other Galaxy Types Habitats of Galaxies 421 Clusters of Galaxies 422 Superclusters of Galaxies 424 Star Party 16.1: Observing Galaxies The Dark Side of Matter 428 NASA, ESA, the Hubble Heritage Team (STScI/AURA)- ESA/Hubble Collaboration, and W. Keel (University of Alabama) The Rotation Curve of the Milky Way Galaxy 428 Dark Matter Everywhere 428 NGC 3314, a chance alignment of two distant galaxies, imaged with the Hubble Space Telescope. The galaxies are actually separated by a distance ten times that of our galaxy from the Andromeda galaxy and are about 140 million light-years from us.

xvi Figure It Out 16.1: Calculating the Mass from the Rotation Curve 429 What Is Dark Matter? 430 16.5 Gravitational Lensing 430 16.6 The Birth and Life of Galaxies 433 16.

10 xvi Figure It Out 16.1: Calculating the Mass from the Rotation Curve 429 What Is Dark Matter? Gravitational Lensing The Birth and Life of Galaxies The Expanding Universe 434 Figure It Out 16.2: Redshifts and Hubble s Law 436 Figure It Out 16.3: Using Hubble s Law to Determine Distances The Search for the Most Distant Galaxies 437 Figure It Out 16.4: Relativistic Effects The Evolution of Galaxies Evolution of Large-Scale Structure QUASARS AND ACTIVE GALAXIES Active Galactic Nuclei Quasars: Denizens of the Distant Past 454 The Discovery of Quasars 454 Puzzling Spectra 455 The Nature of the Redshift How Are Quasars Powered? 458 A Big Punch from a Tiny Volume 458 What Is the Energy Source? 458 Accretion Disks and Jets What Are Quasars? Are We Being Fooled? Finding Supermassive Black Holes 464 Figure It Out 17.1: The Central Mass in a Galaxy The Effects of Beaming Probes of the Universe COSMOLOGY: THE BIRTH AND LIFE OF THE COSMOS Olbers s Paradox An Expanding Universe 479 Hubble s Law 479 Expansion Without a Center 480 What Is Actually Expanding? The Age of the Universe 483 Finding Out How Old 483 The Quest for Hubble s Constant 483 Figure It Out 18.1: The Hubble Time 484 A Key Project of the Hubble Space Telescope 485 Deviations from Uniform Expansion 487 Type Ia Supernovae as Cosmological Yardsticks The Geometry and Fate of the Universe 490 The Cosmological Principle: Uniformity 490 No Cosmological Constant? 490 Three Kinds of Possible Universes 491 Figure It Out 18.2: The Critical Density and Ω M 492 Two-Dimensional Analogues 493 What Kind of Universe Do We Live In? 493 A Closer Look 18.1: Finite Flat and Hyperbolic Universes 495 Obstacles Along the Way Measuring the Expected Deceleration 496 The High-Redshift Hubble Diagram 497 Type Ia (White-Dwarf) Supernovae 497 An Accelerating Universe! 498 Einstein s Biggest Blunder? 499 Dark Energy 500 The Cosmic Jerk The Future of the Universe 502 NASA, ESA, M. Postman (STScI), and the CLASH Team A cluster of galaxies 4.5 billion light-years away, in a Hubble Space Telescope survey that is mapping dark matter.

11 xvii NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team 19 The Hubble Space Telescope's extreme Deep Field (XDF), a small patch of sky at the center of the Hubble Ultra Deep Field assembled from 10 years of observations. IN THE BEGINNING The Steady-State Theory The Cosmic Microwave Radiation 511 A Faint Hiss from All Directions 511 Origin of the Microwave Radiation Deviations from Isotropy 513 Ripples in the Cosmic Microwave Background 513 The Overall Geometry of the Universe 515 The Wilkinson Microwave Anisotropy Probe (WMAP) 516 A Closer Look 19.1: Planck Maps the Cosmic Background Radiation 518 Ground-Based Telescopes for the Cosmic Background Radiation 521 The Planck Spacecraft The Early Universe 522 Going Back in Time 522 A Brief History of the Early Universe 522 Primordial Nucleosynthesis The Infl ationary Universe 526 Problems with the Original Big-Bang Model 526 Infl ation to the Rescue 527 Forces in the Universe 528 Figure It Out 19.1: Infl ation of the Early Universe 529 Supercooling the Universe Successes of Infl ation 532 The Ultimate Free Lunch? 532 Figure It Out 19.2: Heisenberg s Uncertainty Principle A Universe of Universes A Universe Finely Tuned for Life? 534 LIFE IN THE UNIVERSE The Origin of Life Life in the Solar System Suitable Stars for Intelligent Life The Search for Extraterrestrial Intelligence 545 Figure It Out 20.1: Interstellar Travel and Einstein s Relativity Communicating with Extraterrestrials The Statistics of Intelligent Extraterrestrial Life 550 The Drake Equation 550 Where Is Everyone? 551 Figure It Out 20.2: The Drake Equation UFOs and the Scientifi c Method 553 UFOs 554 Of Truth and Theories Conclusion 555 Epilogue 559 Appendix 1. Measurement Systems 561 Appendix 2. Basic Constants 561 Appendix 3. Planets and Dwarf Planets 562 Appendix 4. The Brightest Stars 564 Appendix 5. The Nearest Stars 566 Appendix 6. The Messier Catalogue 568 Appendix 7. The Constellations 570 Selected Readings 571 Glossary 575 Index 585

Astronomy Today. Eighth edition. Eric Chaisson Steve McMillan

Astronomy Today. Eighth edition. Eric Chaisson Steve McMillan Global edition Astronomy Today Eighth edition Eric Chaisson Steve McMillan The Distance Scale ~1 Gpc Velocity L Distance Hubble s law Supernovae ~200 Mpc Time Tully-Fisher ~25 Mpc ~10,000 pc Time Variable